Thursday, October 9, 2014

A quantum jump in Astrophysics

The
highest point in the U.S. state of Hawaii; Mauna Kea is a dormant
volcano located on the island of Hawaii. It stands tall at 13,803 ft
(4,207 m) above sea level. Because of extremely favourable observing
conditions,Mauna Kea's summit is considered as one of the best sites
in the world for astronomical observations. The atmosphere here is
extremely dry. Since the water vapor in the atmosphere absorbs
radiation in submillimeter and infrared region of the
electromagnetic spectrum, Mauna Kea is an ideal spot for
submillimeter and infrared astronomy. The cloud cover always remains
below the summit and keeps the air above the summit free of
atmospheric pollution, stable and without any turbulence. The night
skies are very dark as it is far away from any city lights. All
these factors make Mauna Kea an ideal place to set up astronomical
observatories.

In the
early 1960s, the Hawaii Island Chamber of Commerce began encouraging
astronomical development of Mauna Kea. After 10 long years, a 2.2
meter diameter telescope built by University of Hawaii, UH 88 came
up here. It was the seventh largest optical/infrared telescope in
the world at that time. Today the Mauna Kea Science Reserve has 13
observation facilities, each funded by as many as 11 countries. The
largest facility, commissioned in 1999, has been built by Japan and
is known as the Subaru Telescope, considered as one of the world’s
biggest, it has a single main mirror that measures 8.2 meters in
diameter.

The
main function of any telescope is to collect light from a celestial
object. Once it is collected, a telescope must focus it into a sharp
image. Through careful site selection, enclosure and telescope
design, Subaru was built to obtain the highest resolving power
possible and has superb Light-Collecting and Light-Resolving Powers.
A computer controlled system of support holds the Subaru telescope's
single piece primary mirror in shape with a surprisingly small error
of 0.012 μm (1/5,000,000 inch). The cylindrical shape enclosure
minimizes air turbulence inside, and linear motors drive the solidly
built telescope smoothy and accurately.

Subaru
telescope is soon likely to have a competitor that would have
light-condensing capabilities that would be 13 times greater than the
Subaru telescope’s, which means that the telescope can search for
stars that are less bright or farther from Earth. It should also help
scientists see some 13 billion light years away for a glimpse into
the early years of the universe. This new telescope would be able to
identify an object as small as a coin from a distance equivalent to
500 Km. What makes this new telescope even more interesting venture
for India, is that India is also contributing towards the
construction cost expected to top $1.4 billion and will also have a
share of the observation time. An agreement was signed by The
University of California system, the California Institute of
Technology and the Association of Canadian Universities for Research
in Astronomy with China, India and Japan as partners to construct
this telescope in January 2013.

India
will contribute about Rs 1,300 crore over the construction period
2014-23. with 30 percent of it in cash and balance in kind, to be
spent on vital components of the telescope to be built in India in
partnership with various industries. Indian participation will be
funded by the Government of India through the Department of Science
and Technology (DST) and the Department of Atomic Energy (DAE). The
DST will be the coordinating department for the project.

Initially
China had joined the project as an observer in 2009, followed by
India the next year. Now both are full fledged partners along with
Japan, who already has its own large Subaru telescope at Mauna Kea.
The new telescope is scheduled to be completed in 2022 and would have
its 30 meter diameter primary mirror composed of 492 segments of
1.44 meter diameter each. These mirror segments will be positioned
relative to each other through sophisticated sensors, actuators and
control systems, so that the entire assembly behaves like single
monolithic mirror. This design perhaps has been adopted in light of
a mishap with Subaru telescope wherein there was a coolant leak onto
the primary mirror in July, 2011. The mishap had a significant
impact on functioning of Subaru Telescope and recovery work to put
back telescope back in shape including meticulous inspection and
cleaning of the affected areas took almost two years and was
completed only in the summer of 2013. India would set up a facility
to polish about 100 mirror segments and provide sophisticated
components, like actuators, edge sensors and segment support assembly
for the active optics, which helps in maintaining accurately the
shape of the primary mirror. India will also contribute significantly
to the complex software necessary for the operation of the telescope,
including the telescope control systems and various components of the
observatory software.The Inter-University Centre for Astronomy and
Astrophysics (IUCAA) jointly with the Indian Institute of
Astrophysics in Bangalore and the Aryabhatta Research Institute of
Observational Sciences in Nainital will execute India's contribution
to this project

The
project was launched with a groundbreaking and blessing ceremony to
mark the start of construction, in presence of 100 astronomers and
officials from the five countries on October 7 at a location 4,012
meters high on Mount Mauna Kea. For India, beginning of this project
is particularly of great significance as the largest telescope in
India has only a 2-metre mirror ( on Mt. Saraswati, Digpa-ratsa Ri,
Hanle in south-eastern Ladakh in the eastern Jammu and Kashmir state
of India), though India is building one at Devasthal, Nainital,
Uttrakhand state, that will have 3.6 meter diameter. The new
telescope is likely to be a great boon for Indian astrophysicists and
is surely a quantum jump for study of Astrophysics in India.